Circuit breaker



mcQbmKmsoN ET AL 2,137,873

CIRCUIT BREAKER filed May 29, 1936 Nov. 22, 1938.

5 Sheets-Sheet 1 x INVENTORS aberf dfiickinsarz 45 Pg)? zfzrop 7. Leeds.

Nov. 22, 1938.

R. c. DICKINSON ET AL 2,137,873

CIRCUIT BREAKER Filed May 29, 1936 5 Sheets-Sheet '2 Win27) ap/)ZLeeds. fil fmavwa ATTO EY Nov. 22, 1938. R. c. DICKINSON ET! AL 2,137,373

CCCCCCCCCCCC ER Filed May 29, 1956 5 Sheets-Sheet 3 Nov 22, 1938. R. c. DICKINSON ET AL CIRCUIT BREAKER Filed May 29, 1936 5 Sheets-Sheet 5 INVENTORS Robert C(Dz'ckz'nson & Winthrop 7. Leeds.

ATTORN Y WITNESSES:

Patented Nov. 22, 1938 v UNITED STATES PATENT OFFICE CIRCUIT BREAKER Application May 29,

16 Claims.

This invention relates to circuit breakers and particularly to improvements in arc extinguishing structures therefor.

In the copending application 01 H. J. Lingal a and Rio. Dickinson, Serial No. 743,697, filed September 12, 1934, now Patent No. 2,112,033 issued March 22, 1938, and assigned to the assignee of this application, is shown and described an arc extinguishing structure particularly adapted for operation on high voltage, high power electrical systems. The are extinguishing structure disclosed in the said applicatiowcomprises a plurality of plates of insulating material arranged in a stack and having a narrow aligned slot in 5 each of the plates so as to form a narrow channel or passage of considerable length in which an arc is adapted to be drawn longitudinally thereof by the separation of suitable contact members. The slot-like passage is filled with oil or other suitable arc quenching material which gives oil a gas when acted upon'by an arc. The gas produced by the arc' is known to contain finely divided relatively cool unionized particles which are carried through and are intermingled with the arc stream. Thus as an alternating current are passes through a current zero, there is a strong tendency to deionize the space occupied by the arc stream to such an extent that the are will not restrike when the voltage builds up in the opposite direction. Heretofore, one or two reignitions at the current zero has been considered usual performance, prior to arc extinguishing. The present day demands for high speed circuit interruption, however, makes arc extinguishment at the first current zero very desirable. A

study of the theory of arc extinguishment by means of structures of the type above described has revealed that an increase in the rate of gas liberation greatly accelerates the deionizing action. Movement of the are laterally through the oil or other gas producing material subjects the heat of the arc successively to fresh layers 0! oil,

the rapid decomposition of which thereby provides unionized gas particles in greater quantities.

In order to provide the high rate of gas liberation necessary for are extinguishment of extremely large currents, are velocities have been increased which necessarily demands a longer path of arc travel through the gas producing material.

By giving the arc passage a generally annular shape, as described in the aforesaid application,

an increased length of arc travel can be obtained 1936, Serial no. 82.594 (or 200-) without causing the arc interrupting structure makes the adoption of curved arc passages particularly desirable has, accordingly, complicated the problems or dissipating the gas necessary for are extinguishment. In order to retain the deionizing eflect, the arc must be confined in a relatively narrow passage so that the gas produced by the action of the are upon the oil or other gas producing material will be directed through the arc stream. It will be apparent that particularly in extinguishing structures capable of interrupting a large amount of power, fairly large quantities of gas are generated, accompanied by pressures which. if not relieved, may be destructive to the arc confining structure. It is, therefore, necessary to provide means for proper venting of the arc passage, so that the gas produced during arc extinguishment may escape after performing its deionizing function.

The main object of our invention is directed to the provision of an arc extinguishing structure for circuit breakers oi the type above described in which proper provision is made for enabling the gas produced by the decomposition action of the oil or other gas producing material to escape from the arc extinguishing structure. In order to further meet the demands of high-voltage and high speed are extinguishment, circuit breakers have been provided in which the work or interruption has been apportioned to a plurality oi serially related breaks in which more than two breaks are employed in contradistinction to common practice. A convenient arrangement for a multiple unit construction may consist in mounting the arc extinguishing units end to end for tandem operation. This arrangement, however, requires special consideration of the venting problems of, the individual arc extinguishing units, since during arc interruption the products of combustion of the arc expelled from the arc chamber are apt to cause a flash-over across the ends of each unit.

It is, therefore, a further object of our invention to provide venting means for a. multiple unit are extinguishing structure which reduces the flashover hazard, across the units, to a minimum.

Other objects and advantages relate. to details of the extinguishing structure and will appear more fully in the following description taken in connection with the accompanying drawings, in which;

Figure 1 is a side elevation partially in section of a multiple break circuit breaker embodying our invention,

Fig. 2 is a vertical sectional view taken along the line lI--Il of Fig. 3 showing one of the upper arc extinguishing units of the breaker arc extinguishing assemblage.

Fig. 3 is a cross sectional view of the upper arc extinguishing unit shown in Fig. .2 and taken along the line 111-111 01' that figure,

Fig. 4 is a'iragmentary sectional view o! the arc extinguishing unit Fig.2 and taken along lines be illled with oil or some other suitable ,m'

quenching medium, and is provided at the upper end thereof with a pair of insulating bushings 2 through which the line terminals 3 of the circuit breaker are conducted interiorly of the tank. To the-lower end of each of the terminal members 3 is secured an arc extinguishing assemblage generally indicated at 5. Each of the arc extlnguishing assemblages comprises a series of arc extinguishing units I which are arranged end to end in spaced relationfas shown. Each of the units l. as will appear more fully hereinafter, is provided with a pair of separable contacts which are connected in series so as to provide an arc circuit from the incoming terminal 3 through the are extinguishing assemblage 5 to a releasable contact member 9 at the lower end of each assemhlage 5.

The releasable contact members 9 are adapted to be electrically connected to each other by means of a bridging bar I I, in this instance moved into and out of engagement with the contact members 9 by a lift rod l3 which is actuated by a I suitable operating mechanism not shown.

- Each of the units I, as more particularly shown in Fig. 2, comprises a plurality of plates of insulating material designated as l5 and [1 respectively. Each of the-plates l5 and II have relatively narrowcircular slots extending therethrough, which slots are adapted to be aligned when the plates are arranged in a stack so as to form an annularly shaped narrow passage designated at I 9. I The plates ii are provided with indentures or recesses adjacent the sides of the slot, so as to provide pockets 2! along the'sides of the slot for entrapping oil or other suitable arc quenching liquids. The ends of the passage l9 are enclosed by plates 23 also of insulating material. To each end of the stack is also applied end plates 24 and 25 of magnetic material. The entire stack assemblage is adapted to be held together by a plurality of tie rods 21. preferably 01 insulating material and passing axially through the stack a.

adjacent the peripheral edge thereof, as shown. The individual units I comprising an are extinguishing assemblage 5 may be held in spaced relation with respect to each other by means of tie rods 3i also passing axially through each of the units I and through suitable spacing members 33 interposed between the adjacent units 1.

are exbiasing action of the spring 53.

The upperends of the tie rods 9] are 'bolted to a contact foot 35 which, in turn, has threaded engagementv with the lower end of the incomingterminal 3. Each of the arc extinguishing units 1 is provided with a pair of separable contacts, a fixed one 81 which-is adapted-to'be electrically connected to the upper magnetic end plate 24 and a movable one 39 which is-adapted to .be

moved into and out otengagement with the fixed contact 81 through a suitable guide member ll positioned in theiower magnetic end plate 25.-

The movable contact "is adapted to be actuated by a straight line actuating mechanism, generally indicated at-l3, andwhich mechanismmakes pivotal connection by means of a pin 45 to an actuating rod 41 passing through the central portion of the stack of plates constituting theunit'l.

.The upper end of the operating rod 41 is provided with a guide member 49 adapted to operatively engagethe walls of a cylindrical cap membcr 5|. A coil spring 53 surrounding a guiderod 55 projecting from the end or the member 49 is interposed between the end of the cylindrical cap member ii and the member 49, andserves to actuate the rod 41 to the open circuit position.

Although only the uppermost unit I is shown 1 in Fig. 2,-it will be understood'that the remain-.

ing or the subsequent units are similar in construction, eachhaving a separable pair of contacts 31 and 39:01 which the movable contact is actuated by a mechanism 53. Each'of the mechanisms 43 of each assemblage 5 are operatively coupled to the single actuating rod 4-! which extends the full length of the arc extinguishing assemblage. The releasable contact members 9 are respectively mounted upon the lower ends of the two operating rods 41. w

As the lift'rod I3 is moved into the closed po-' sition, the bridging bar ll engages the releasable contacts 9 and moves the two operating rods 41 to the uppermost or closed position against the Thus when the breaker is tripped, the holding mechanism associated with the lift rod i3 is released,thereby allowing the spring 53 to move theoperating rod 41 of each arc extinguishing assemblage 5 downwardly so as to simultaneously separate the conthe lower end plate 25 of the uppermost unit I with the upper end plate 24 of the next adjacent unit I.

It will be apparent that the circuit through the succeeding units 1 will be the same as that de scribed in connection with the first or upper- .most unit. Connection from the lowermost end plate 25 of the lower uni I is made by a flexible shunt, not shown. to the respective releasable contact 9 mounted upon the end of the operating rod 41. From one of the contact members 9 the circuit continues through the bridging bar I I, the other contact member 9 and then through the other are extinguishing'assemblage 5 and to the other line terminal 3.

The are which hasbeenlestablished as a result of the movement of the contact member 38 toward the open position will'be transferred to a pair of arcing horns 85 and 81, the former lying in the upper end of the passage I8 and being supported by the upper end plate 23 of insulating material. The latter horn 81 is disposed in the lower end of the passage l8 and is preferably mounted upon the lower insulating end plate 23. The are horns- 85 and 81', respectively, are providedwith are receiving tips 88 and 1|. The, horns generally have a circular shape and extend throughout a substantial portion of the circumference of the passage I 8. The remaining portion of the passage l9, that is, the spacing between the end of the respective horns 65 and $1 and the contact members 31 and 39. is provided with insulating barriers or deflectors designated at 13 and 15, respectively, the purpose of which will appear more fully hereinafter.

It will be noted that the arc receiving tip 69 01' the arc horn 65 extends downwardly into the passage 19 some distance beyond the lower edge 0! the fixed contact 31. Thus as the movable contact 39 separates from the fixed contact 31, an arc will be drawn therebetween, but

; since the movable contact 39 travels closely adjacent to the arcreoeiving tip 68, the arcwill transfer from the main contact 31 to the arc horn 85.

The magnetic end plates 28 and 25 are each provided with an annular recess 11 in which coils 18 and 19, having low resistance and a relatively small number of turhs, are embedded. One end of the upper coil 18 is connected tov the upper "end plate 28, whereas the other end of the upper coil 18 is connected to the upper arc horn 65. The lower coil 19 is similarly connected in that it has one end connected to the lower plate 25, and its other end connected to the lower arc horn 81. The specific connections of the coils I 18 and 18 are not shown since they may be eiiected in any conventional manner. Thus, as the moving contact 39 is drawn past the lower edge of the arc receiving tip 69, the "arc from the fixed contact 31 will transfer thereto and since the voltage drop across the upper coil 18 and the arc horn 65 is not sufilcient to maintain the are between the fixed contact 31 and the moving contact 39, that portion of the arc will be extinguished.

As soon as the arc transfers from the fixed contact 31 to the arc horn 65, the upper coil 18 is inserted into the arc circuit. The'energization of the upper coil 18 immediately sets up the radial magnetic field across the upper end of the passage, l8 which assists in moving the lower end of the are from the movable contact 31 onto the lower arc horn 81. Upon the transfer of the lower end of the arc tb the lower arc horn 61, the lower coil 18 is also inserted in the arc circuit and the arc current circuit for each unit then is from the upper end plate 24 through the upper coil 18, are horn 85, are horn 61, the lower coil 19 and the lower end plate 25. The magnetic field produced by the lower coil 19 operates jointly with that produced by the upper coil 18 to create a strong radial magnetic field across the greater portion of the passage I 9.

The radial magnetic field thus produced causes the arc to rotate along the passage IS in a counter-clockwise direction as viewed in Fig. 3 with its ends in engagement with the arc 'horns 85 and 81. Immediately upon the initiation of the are between the contacts 31 and 39 part of the oil or other are quenching media within the passage I8 is decomposed and the arc is soon surrounded by a gas bubble. As soon as the magnetic field operates upon the arc, it is believed that the arc is driven to one side of the gas bubble surrounding it, thereby engaging a fresh wall of oil which, in turn, creates more gas and large quantities of relatively cool unionized particles which of necessity must flow-back through the arc stream.

When the arc current passes through current zero, the eifect of the relatively cool unionized gas particles is to build up the dielectric strength of the space formerly occupied by the arc stream to such an extent that the arc will not restrike upon the voltage building up in the opposite direction. The rapid movement of the arc by means of a strong-radial field as is capable of being produced by the upper and lower coils 18 and 19,'causes an ample quantity of relatively cool gas to be produced for-deionizing purposes. If the arc is moved at'a sufiiciently high rateof speed and enough gas is produced by decomposition of the oil when acted upon by the heat of the arc, arc extinguishment may take place at the first current zeror It will be apparent'that the production oi a sufliclent quantity of gas to eflectively extinguish the arc in such a short time interval may create -.so high a pressure within the passage i8 as to cause mechanical failure of the structure. It

; escape from the chamber for passage l8.

As shown in Figs. 2, 3 and 4, the arc horns 85 and 81 are provided with slot-like passages 8| spaced, as particularly shown in Fig. 3, throughout the length of the horns. These passages or conduits 8| are adapted to be aligned with similar passages 83 extending axially through the end plates 23, 24 and 25. It will thus be seen that the passages 8i and 83 will provide adequate means for the escape of gas and also oil or any other product of decomposition resulting from the formation and extinguishment of an arc within the passage i9- It will be noted that as the arc is moved along the horns 65 and 61, the gas produced as a result of the advancing portion of the arc contacting the oil contained within the passage I9 will flow back through the arc stream and hence out of the openings created by the passages 8i and 83. Inasmuch as the vent'openings 8| and 83 are located through the arc horns respectively at the upper and lower ends of the passage i9, con siderable longitudinal flow of gas in the arc in addition to the transverse flow takes place, thereby increasing the turbulence of the gas in the arc stream which further aids in extinguishing the arc. i 4

It will be noted that the insulating end plates 23 are extended beyond the insulating plates l5 and I1 forming the main body portion of the arc extinguishing units and the metallic end plates 24 and 25. The projecting portions of the end plates 23 provide bailles between the metallic end plates 24 and 25 of each unit 1 so as to increase the creepage distance between these plates, particularly during the discharge of large In order to further lessen the danger of flashover, the upper end plate 24 may be surrounded with a relatively short cylindrical baiile 85 of insulating material (Fig. 4). The baffle 85 not only deflects the gas upward after being expelled from the vents, but also increases the creepage distance from the end plates 24 to the lower end plate 25. The baffle 85 also prevents any foreign matter which may be expelled through the vent openings 83 of the upper plate 24 from being washed over the sides of the unit 1, thereby further decreasing the fiashover hazard.

The insulating deflectors l3 and 15 positioned between. the terminating ends of the arc horns 65 and Bland the contact members 31 and 39 previously referred to, are utilized to deflect the oil in the passage 19 which is caused to be placed into circulation by the rotating movement of the arc in the passage. The introduction of the deflectors l3 and 15 causes a gradual diminution of passage length on one side of the contacts 31 and 39 whereas the are receiving tips 68 and H have a similar effect on the opposite side of the contacts. Inasmuch as the passage is materially shortened in the region of the contacts 31 and 39, and also at the are receiving tips 69 and II, the velocity of the oil will be materially increased due to Venturi action. This increase in velocity is helpful in replacing gas with fresh oil at the place of least separation between the arc horns 65 and 61, thereby further insuring that when the arc has been extinguished that it will not restrike at that point.

Although the arrangement of a number of vent openings 8| and 83 distributed along the arc horns 85 and 6'! provides a more ready egress for the gas from the arc passage I9, it does so at the expense of a greater loss of oil from the arc passage than would result if a single vent slot of appropriate dimensions were placed through the arc horns adjacent the contacts. In the latter form of construction the gas produced by the are acting upon the oil as it advances along the arc horns 65 and 61 in a counter-clockwise direction, as viewed in Fig. 3, will flow back through the arc stream causing deionization and then escape through the vent opening adjacent the contacts 31 and 39. The oil in the passage will, due to the rotation of the arc and assisted by the gas pressure produced by the are acting thereon, be caused to circulate in a counter-clockwise direction and be in part forced out of the vent openings. However, if the vents are located through the arc horns adjacent the contacts 31 and 39, the oil must flow across the contacts and are receiving tips 69 and ll before it reaches the vent openings.

In Fig. 5, a modified means of venting the passage (9 has been shown. Instead of carrying the venting passages axially through the end plates of each unit 1, a number of radial passages 9i uniformly distributed lengthwise of the passage are provided.

Although this particular method of venting may not be as effective as the venting means shown in the previously discussed figures, it has the advantage of cheaper construction, and perhaps subjects the arc to a more violent crossfiow of gas at intervals when the are is immediately adjacent one of the passages 9|. As described in the previous figures, the projections of the insulating end plates 23 also provide baffies for preventing fiashover as a result of the gas being discharged between the metallic end plates 24 and 25.

In Figs. 6 and 7, a slightly modified form of arc extinguishing structure is shown. In these figures the arc passage I9 is not continuous or recurrent, as shown in the previous figures, but extends substantially through an arc of 270 more or less. The general outline of the side walls of the passage I 9, however, is similar to that previously described. The are horns 65 and 61 have the same general conformation as those previously described and are supported by the insulating end plates 23.

The venting means in this instance comprise a generally annularly shaped chamber llll concentric with the passage [9 and formed in the upper and lowermost insulating plate IS. The annular shaped chamber lfll 'is connected by means of radial ports N33 to the arc passage [9. The ports I03 are spaced angularly from each other throughout the length of the arc travel, so as to provide substantially uniform access of the gas produced in the passage I! to the annular chamber I M Chamber ilil has outwardly projecting nodes I05, each of which are adapted to communicate with an axially directed passage I01 extending through both the insulating and magneticend plates 23, 24 and 25.

It will thus be seen that both the upper and lower ends of the arc passage l 9 are freely vented into the space between adjacent units 1, which space is bounded by the metallic end plates 24 and 25 of two adjacent units, which plates are maintained at the same electrical potential. In the modified form, as shown in Figs. 6 and 'I, the projecting baflle portions oi the insulating end plates 23 also decrease the flashover hazard across end plates 24 and 25 in the manner previously described. 4

In connection with the particular arrangement of venting means shown in Figs. 6 and 7, it may be pointed out that this arrangement-provides highly satisfactory arc extinguishing operations over a wide range of current values. However, the extinguishment .of relatively low current arcs and relatively high current arcs can be considerably improved by separate treatment of the arrangement of the arc passage venting means. We have found that for low currents improved operation can be obtained by concentrating relatively small vent openings at the ends of the passage near the contacts. The low cur rent arc, due to its relatively weaker radial field strength in the arc passage l9, tends to move only a very short distance along the passage before it is extinguished. Also, since the low current arc decomposes very little of the arc quenching liquid in the passage, the gas pressure maynot reach a value which is favorable to arc extinction. Therefore, by placing the vent openings near the contacts the movement of the arc is assisted by the motion of the liquid toward the vent openings, and also by keeping the vent openings small, the pressure will rise sufliciently to maintain adequate dielectric between the contacts.

On the other hand, we have found that the concentration of larger vent openings at the ends of the arc passage adjacent the ends of the are horns 65 and 61 farthest from the contacts is more efiective for the extinguishment of currents of greater magnitude. The reason for expecting a more eflicient operation under these conditions is as follows: although under the influence of a proportionately higher strength radial magnetic field produced by the coils 19, may not move at a much higher velocity than arcs of low current magnitude due Arcs of high current magnitude,

to the high resistance to motion of arcs of large cross section in a restricted slot. However, by providing vents at the ends of the arc horns farthest from the contacts a considerable portion of the arc quenching liquid in the passage I9 will be expelled through the vent openings, and more rapid motion oi the are relative to the slot facilitated. This allows the arc extinguishing gas in back of the arc stream to be scattered over a greater distance, and a continuous ionized path for breakdown made less likely. After arc extlnguishment, the trapped gas may escape from the arc passage is through the vents provided therefor, thereby allowing the passage to refill with arc quenching liquid.

It will be apparent that any of the foregoing types of vent openings leading from the arc passage may be employed in the particular arrangements last described for obtaining more efiicient operation 'for the extinguishment of arcs of low and high current magnitude.

From the foregoing description, it will be apparent that we have provided an arc extinguishing structure which is particularly adapted for high voltage and high speed arc interruption service. We have also provided an arc extinguishing unit having an arc passage therein which is adequately vented, thereby making high power, high speed extinction possible without increasing the hazard of failure of the arc extinguishing unit due to fiashover which may result from the dischargeof the products of decomposition of the arc from within the unit. Furthermore, we have provided a particular are extinguishing unit and venting means therefor peculiarly adapting the unit for multiple arrangement in a multiplebreak circuit interrupter.

Although we have shown and described particular structural arrangements for carrying out the objects of our invention, it is to be understood that the same is for illustrative purposes and that changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the appended claims,

We claim as our invention:

1. In an arc extinguisher, means of insulating material for defining the walls of a generally annularly shaped narrow arc passage, means for establishing an are at a predetermined position within said passage, stationary arc terminal means of generally circular shape at each end of said are passage for receiving the ends of said are, a coil for setting up a magnetic field radially across said passage for moving said arc along said passage with its ends in engagement with said are terminal means, a material along said passage which gives off a gas when acted upon by an arc to aid in extinguishing the arc, said arc passage being closed at-its end adjacent both the inside and outside of said circular arc terminal means, and a plurality of openings through said are terminal means leading exteriorly of said arc extinguishing structure to cause the gas produced by the arc to pass laterally and longitudinally through said are and escape through said openings.

2. In an arc extinguisher, a stack of plates of insulating material, each of said plates having a narrow generally circular slot therethrough, said slots being aligned to form a generally annularly shaped arc passage of considerable length, means for enclosing the ends of said passage, means for establishing an arc of considerable length within said passage, arc terminal means within said passage for receiving said arc, means terminal means, a material along said passage which produces a gas when acted upon by an arc to aid in extinguishing the arc and vent means comprising a plurality of openings disposed at spaced intervals circumiere'ntially of and adjacent to said are terminal means. and leading radially from said passage'exteriorly of said stack of plates to enable the gas to escape -from said passage,

3. In an arc extinguisher, a stack of plates of insulating materlalfeachof said plates having a narrow generally circular slot therethrough, said slots being aligned. to form 'a generally annularly shaped arc passage of considerable length, means for enclosing the ends of said passage, means for establishing an arc of considerable length within said passage, an arc terminal at each end of said passage for receiving the ends of said arc, a coil for establishing a radial magnetic field acrosssaid passage for rotating the arc laterally in one long section therein lie-- tween 'said arc terminals, a material along said passage which gives off a gas when acted upon by an arc to aid in extinguishing the arc, and venting means at each end or said passage comprising a duct having a portion leading radially from said passage adjacent an arc terminal and a second portion positioned for discharging gas axially of said passage. 1

4, In an arc extinguisher, aplurality of plates of insulating material each of which is provided with a curved narrow slot therethrough. said plates being arranged in a stack with their slots in alignment to form a generally annular passage, end plates 01 insulating material for enclosing the ends of said passage, means for establishing an are within said passage, means for rotating said are in said passage, and venting means adjacent at least one end of said stack for the gases produced by the action 03 said arc comprising a duct leading from the end of said passage and terminating in an axial direction with respect to said passage.

5. In an arc extinguisher, a plurality of plates of insulating material each or which is provided with a curved narrow slot therethrough, said plates being arranged in a stack with their slots in alignment to form a generally annular passage, end plates of insulating material for enclosing the ends of said passage, means for establishing an are within said passage, means for rotating said arc in said passage, and venting .means for at least one end of said passage comprising an annularly shaped chamber within said stack adjacent the end of said passage, ports connecting the end of said passage and said chamber and ducts leading from said chamber axially through the end of said stack.

6. In an arc extinguisher, a plurality of plates of insulating material, each of which is provided with generally circular narrow slots therethrough, said plates being arranged in a stack with their slots in alignment to form a generally annular passage and plates of insulating material for enclosing the ends of said passage, means for establishing an are within said passage, an

arc horn at each end of said passage for receiving the ends of said arc, a coil for setting up a radial magnetic field across said passage for moving the arc between said arc .horns, a fluid in said passage which gives off a gas when acted upon by an arc to aid in extinguishing the arc, and 'venting means adjacent at least one end of said passage comprising 'an annularly shaped chamberwithinsaid stack adjacent the end or establishing a series arc'within each or said passages, each of said passages having a'material therealong which gives oil a gas when acted upon by an arc to aid in extinguishing the arc, vent means for each unit adjacent the ends thereof only to enable gas to escape from the passage within each of said units, the passage of each unit-being completely enclosed except for said vent means, and means associated with each unit for confining the discharge gases to prevent flashoverexteriorly of the units during or im- -mediately following a circuit interruption.

8. In a circuit breaker, an arc interrupting assemblage comprising a plurality of arc extinguishing units, each of said units having means of insulating material for defining the walls of a generally annularly shaped arc passage, said units being arranged end to end in spaced relation with their respective arc passages in axial alignment, means for simultaneously establishing a series are within each of said passages, means for producing a magnetic fleld radially across each of said passages for rotating each arc. along its respective passage, each 01' said passages having a material therealong which gives oiI a gas when acted upon byan arc to aid in extinguishing the arc, venting means for eachunitleading from the passage within the unit and discharging into the space between adjacent units, and baiiie means 01 insulating material positioned adjacent the ends 0! each unit for increasing the leakage path across each unit to prevent fiashover exteriorly of each unit.

9. In a circuit breaker, an arc interrupting assemblage comprising a plurality of arc extinguishing units, each of said units having means of insulating material fordefining the walls of a generally annularly shaped arc passage, said units being arranged end to end in spaced relation with their respective arc passages in axial alignment, means for simultaneously establish ing a series arc within each of said passages, means for producing a magnetic field radially across each of said passages for rotating each are along its respective passage, each of said passages having a material therealong which gives oil? a gas when acted upon by an arc to aid in extinguishing the arc, vent means for each unit comprising at least one duct leading from said passage through at least one end oi each unit, and battle means positioned adjacent the ends of said units for preventing the gases discharged iroin said vent means from causing a flashover across each unit during or immediately following a circuit interruption.

10. In a circuit breaker, an arc interrupting assemblage comprising a plurality of arc extinguishing units, each of said units comprising a plurality of circular plates of insulating material each plate being provided with a generally circular narrow slot therethrough, said plates being arranged in a stack with their slots in alignend to end in spaced relation with their are passages in axial alignment, means for simultanecusly establishing a series arc within each 01' said passages, a coil operatively associated with each of said end plates of magnetic material for setting up a magnetic field across said passages to rotate the are established in each passage therein, a material along each passage which gives oil a gas when acted upon an arc to aid in extinguishing the arc, venting means comprising a plurality of ducts leading from the ends of each passage through the respective end plates of each unit and discharging into the space between said units, said end plates 01 insulating material having a diameter greater than the diameter or said slotted plates and said end plates of magnetic material to increase the creepage distance between the magnetic and plates of each unit, and an annular member oi! insulating material surrounding theupper magnetic end plate of each unit to deflect the gas'expelled through said venting means in a direction away from the lower magnetic end plate of the same unit. 4

11. In an arc extinguisher, a plurality of plates of insulating material each of which is provided with a curved slot therethrough, said plates being arranged in a stack with their slots in alinement to form a generally annularly shaped passage of considerable length, end plates of insulating material for enclosing the ends of said passage, 8. pair oi separable contacts within said passage for establishing an arc of considerable length therein, means for rotating said are in one long section in said passage, and venting means adjacent at least one end of said stack comprising an opening through the insulating material leading from said passage at a point adjacent said electrodes to the exterior of said stack.

12. In an arc extinguisher, a plurality of plates of insulating material each of which is provided with a curved slot therethrough, said plates being arranged in a stack with their slots in alinement to form a generally annularly shaped passage of considerable length, end plates of insulating material i'or enclosing the ends of said passage, a pair of separable contacts within said passage for establishing an arc of considerable length therein, an arc-horn at each end of'said passage having one end lying adjacent said separable contacts, means for moving said are in one long section with its ends in engagement with said are horns along said passage, and venting means adjacentiat least one end of said stack comprising an opening leading from said passage at a point adjacent the other end of one -of said arc horns to the exterior of said stack.

13. In a circuit interrupter, an arc-extinguishing structure comprising means of insulating material defining a narrow generally annularly shaped arc passage, a pair of contacts within said are passage, means for causing a predetermined separation of said contacts to establish an are solely within said are passage at a predetermined position, an arc terminal member of arcuate shape disposed in fixed relation at each end of said passage, each of said are terminal members having one of their ends positioned adjacent one of said contacts for receiving the ends of the are drawn between said contacts, means along said arc passage which gives off a gas when acted upon by an arc to aid in extinguishing the arc, means for moving the arc laterally in one section between said arc terminal members, and vent openings for the products of decomposition of the arc leading from at least one end of said arc passage to the exterior of said arc-extinguishing structure, saidivent openings being disposed adjacent to and circumferentially of said arc terminal members to subject the arc during its movement along said arc terminal members to a longitudinal flow of the products of decomposition during the escape of said products from the arc passage.

' 14. In a circuitinterrupter, an arc-extinguishing-structure comprising means of insulating material defining a narrow generally annularly shaped arc passage of considerable length,'means for establishing an arc of considerable length within said passage, an arc terminal at each end of said passage for receiving the ends oi said arc, a coil for establishing a radial magnetic field across said passage for rotating the arc laterally in one long section between said arc terminals, a material along said. passage which gives off a gas when acted upon by an arc to aid in extingushlng the arc, and venting means at each end of said passage comprising a duct having a portion leading radially from said passage adjacent an arc terminal, and a second portion positioned for discharging the products of decomposition of said arc axially of said passage.

15. In a circuit interrupter, an arc-extinguishing structure comprising means of insulating material defining .a narrow generally annularly shaped arc passage, means for enclosing the ends of said passage, means for establishing an are within said passage, means for rotating said are in said passage and venting means for at least one end 0! said passage comprising an annularly shaped chamber within said means of insulating material adjacent-the end of said passage, ports connecting the end of said passage and said chamber, and ducts leading from said chamber axially through the end of said arc-extinguishing structure.

16. In an arc extinguisher, means of insulating material defining the walls of a narrow generally annularly shaped arc passage in which an arc of considerable length may be established, said arc passage being closed at its ends, an arc horn at each end of said are passage for receiving the ends oi. an arc and between which the arc is adapted to be moved, a coil for setting up a radial magnetic field across said passage for moving the are between said are horns, a fiuid in said passage which gives oil a gas when acted upon by an arc to aid in extinguishing the arc, and venting means adjacent at least one end of said passage comprising an annularly shaped chamber within said means of insulating material adjacent the end of said passage and concentric therewith, a plurality of radially extending ports joining said passage and said chamber and a plurality of ducts leading axially,

from said chamber through the end of the arcextinguishing structure.

ROBERT C. DICKINSON. WIN'I'HROP M. LEEDS. 

